1. Field of the Invention
The present invention relates to a hybrid wiring board, and more particularly to a hybrid wiring board with a built-in stopper, which includes an interposer, a stopper, a stiffener and a build-up circuitry.
2. Description of Related Art
Conventional flip-chip package includes a semiconductor die that is flipped and bonded to a laminate substrate through an array of solder bumps. The matching contact pads of the laminate substrate typically have a finer pitch than that of the backside contact pads so that the laminate substrate can accommodate high I/O chip and allow the assembled package easily attaches to a printed circuit board for next level assembly. To meet even finer feature and higher performance requirements, modern semiconductor chip incorporates a low-k dielectric as the interlayer material. As low-k dielectric material is porous, fragile and very sensitive to the interfacial stresses, conventional flip chip packages encounter various reliability and yield loss issues due to CTE mismatch between the low-k die and the laminate substrate. Therefore, incorporating a through-via interposer which has a similar CTE to that of the low-k die as a buffer is desirable to resolve the manufacturing yield and reliability concerns.
Various through-via interposers such as silicon, glass or ceramic which have similar CTE to that of the silicon are suitable for this purpose. The through-via interposer can be attached to a laminate substrate by solder bumps or it can be embedded in a build-up circuitry to form a hybrid wiring board so that the overall electrical performance can be further improved. However, as the hybrid wiring board is a non-symmetrical structure and the interposer has a different CTE to that of the build-up circuitry, a warp of the hybrid wiring board can easily occur and this will result in a not mountable interposer for low-k semiconductor chip. Furthermore, as the interposer needs to be mounted on the circuitry first before forming a highly precise conductive via for interconnection, it is impossible to align the contact pad with a laser beam if the interposer placement accuracy is not secured or if the die attach adhesive underneath the interposer “reflow” during the adhesive curing stage. As a result, a deterioration of yield or reliability might be caused.